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5.measurement

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Contains Research methodology might be useful to medical and paramedical UG and PG students pursuing Research

Contains Research methodology might be useful to medical and paramedical UG and PG students pursuing Research

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  • 1. Measurement andscaling techniquesD.A. Asir John Samuel, MPT (Neuro Paed), Lecturer, Alva’s college of Physiotherapy, Moodbidri Dr.Asir John Samuel (PT), Lecturer, ACP
  • 2. Data• Data / variable Data Quantitative QualitativeDiscrete Continuous Nominal Ordinal Dr.Asir John Samuel (PT), Lecturer, ACP
  • 3. Quantitative• Discrete- Takes only specified no.of values in a given range- E.g. No. of birth Dr.Asir John Samuel (PT), Lecturer, ACP
  • 4. Quantitative• Continuous- Theoretically can take any value with in given range- E.g. BP, Wt, Ht, age, Dr.Asir John Samuel (PT), Lecturer, ACP
  • 5. Qualitative• Cannot be measured numerically• Nominal- No nature order among the categories- E.g. gender, religion, etc., Dr.Asir John Samuel (PT), Lecturer, ACP
  • 6. Qualitative• Ordinal- Natural ranking of categories- E.g. severity of diseases, socioeconomic status, Dr.Asir John Samuel (PT), Lecturer, ACP
  • 7. Scales of measurement Scales Categorical NumericalNominal Ordinal Interval Ratio Dr.Asir John Samuel (PT), Lecturer, ACP
  • 8. Nominal scale• Lowest level of measurement• Used for variable that are qualitative• Variable is divided into several categories• Frequently allow us to compare no.of items within each category• No arithmetic operation are permitted• E.g. gender, religion, etc., Dr.Asir John Samuel (PT), Lecturer, ACP
  • 9. Ordinal scale• Rank order the objects being measured• Permissible operations are < = >• No meaning of magnitude of difference between adjacent units on scale• Does not have the property of equal intervals between adjacent units• No arithmetic equation permitted• E.g. pain score, disease severity, etc., Dr.Asir John Samuel (PT), Lecturer, ACP
  • 10. Interval scale• Have real number system properties of order and distance but lack origin• Possess all the properties of the ordinal scale• Equal intervals b/w adjacent units• Does not have an absolute zero point• Permissible arithmetic operation are - & +• E.g. temp in Celsius, IQ score, etc., Dr.Asir John Samuel (PT), Lecturer, ACP
  • 11. Ratio scale• Exhibit all 3 components of real number system: order, distance and origin• Highest level of measurement scale• Possesses all the properties of interval scale• Has an absolute zero point• Permissible arithmetic operations are, -, +, x and /• E.g. wt, ht, distance, etc., Dr.Asir John Samuel (PT), Lecturer, ACP
  • 12. Sources of error in measurement• Respondent• Situation• Measurer• instrument Dr.Asir John Samuel (PT), Lecturer, ACP
  • 13. Respondent• Reluctant to express strong negative feelings• May have very little knowledge but may not admit ignorance• Result in an interview of guesses• Limit ability to respond accurately and fully Dr.Asir John Samuel (PT), Lecturer, ACP
  • 14. Situation• Any condition which places strain on interview• Affects interviewer-respondent rapport• Can distort responses by joining in or merely by being present Dr.Asir John Samuel (PT), Lecturer, ACP
  • 15. Measurer• Distort responses by rewording or reordering questions• Behaviour, style and looks may encourage or discourage certain replies from respondents• Incorrect coding• Data-analysis stage Dr.Asir John Samuel (PT), Lecturer, ACP
  • 16. Instrument• Defective measuring instrument• Complex words• Beyond comprehension• Poor sampling Dr.Asir John Samuel (PT), Lecturer, ACP
  • 17. Technique of developing measurement tools• Four-stage process- Concept development- Specification of concept dimensions- Selection of indicators- Formation of index Dr.Asir John Samuel (PT), Lecturer, ACP
  • 18. Meaning of Scaling• A procedure for the assignment of numbers to a property of objects in order to impart some of the characteristics of numbers to the properties in question• Quantitative measures of subjective abstract concepts Dr.Asir John Samuel (PT), Lecturer, ACP
  • 19. By 2 ways• Making judgement• Constructing questionnaires Dr.Asir John Samuel (PT), Lecturer, ACP
  • 20. Technique of developing measurement tools• Concept development• Specification of concept dimensions• Selection of indicators• Formation of index Dr.Asir John Samuel (PT), Lecturer, ACP
  • 21. Concept development• First and foremost step• Researcher should arrive at an understanding of major concepts pertaining to his study• More apparent in theoretical studies than in the more pragmatic research Dr.Asir John Samuel (PT), Lecturer, ACP
  • 22. Specification of concept dimensions• Specify the dimensions of the concepts developed in first stage• Accomplished by,- Deduction- Correlation of individual dimensions with concept Dr.Asir John Samuel (PT), Lecturer, ACP
  • 23. Selection of indicators• Measuring each concept• Specific questions, scales or devices by which respondent’s knowledge, opinion, expectation, etc are measured• Researcher should consider several alternatives as there is seldom perfect measure Dr.Asir John Samuel (PT), Lecturer, ACP
  • 24. Formation of index• Combining several dimensions of concept or different measurement• Provide scale values to responses and sum up the corresponding scores• Has probability relation to what we really want to know Dr.Asir John Samuel (PT), Lecturer, ACP
  • 25. Classification of scales• Subject orientation• Response form• Degree of subjectivity• Scale properties• Number of dimensions• Scale construction techniques Dr.Asir John Samuel (PT), Lecturer, ACP
  • 26. Subject orientation• Measure characteristics of respondent who completes or to judge stimulus object• Homogeneous stimuli are presented• Between stimuli variation is small Dr.Asir John Samuel (PT), Lecturer, ACP
  • 27. Response form• Classify scales as categorical and comparative• Categorical scales – rating scales, used when respondent scores without direct ref. of other• Comparative scales – ranking scales, used when comparing b/w two or more objects Dr.Asir John Samuel (PT), Lecturer, ACP
  • 28. Degree of subjectivity• Subjective personal preferences or simply make non-preference judgement• Choosing which person he favours• Judge which person is more effective Dr.Asir John Samuel (PT), Lecturer, ACP
  • 29. Scale properties• Classify scales as,• Nominal• Ordinal• Interval• Ratio scales Dr.Asir John Samuel (PT), Lecturer, ACP
  • 30. Number of dimensions• Unidimensional or multidimensional scales• Measure only one attribute of respondent• Describes concept of attribute space of ‘n’ dimensions Dr.Asir John Samuel (PT), Lecturer, ACP
  • 31. Scale construction techniques• Arbitrary approach (based on assumption)• Consensus approach• Item analysis approach• Cumulative scales• Factor scales Dr.Asir John Samuel (PT), Lecturer, ACP
  • 32. Scaling techniques• Arbitrary scales• Differential scales/Thurstone-type scales• Summated scales/Likert-type scales• Cumulative scales• Factor scales Dr.Asir John Samuel (PT), Lecturer, ACP
  • 33. Arbitrary scales• Designed through researcher’s own subjective selection of items• Collects few statements or items which he believes appropriate to a given topic Dr.Asir John Samuel (PT), Lecturer, ACP
  • 34. Arbitrary scales-Merits• Can be developed very easily and quickly• Relatively less expensive• Highly specific and adequate Dr.Asir John Samuel (PT), Lecturer, ACP
  • 35. Arbitrary scales-Demerits• Do not have objective evidence• Simply rely on researcher’s insight and competence Dr.Asir John Samuel (PT), Lecturer, ACP
  • 36. Differential scales/Thurstone-type scales• Developed using consensus scale approach• Selection is made by panel of judges• Evaluate whether they are relevant to the topic area Dr.Asir John Samuel (PT), Lecturer, ACP
  • 37. Summated scales/Likert-type scales• Item analysis approach• Particular item is evaluated on basis of how it discriminates b/w those persons whose total score is high and low• Items that best meet this sort of discrimination test are included in final statement Dr.Asir John Samuel (PT), Lecturer, ACP
  • 38. Summated scales/Likert-type scales1. Strongly agree2. Agree3. Undecided4. Disagree5. Strongly disagree Dr.Asir John Samuel (PT), Lecturer, ACP
  • 39. Advantages• Easy to construct• More reliable• Respondent-centered• Less time to construct Dr.Asir John Samuel (PT), Lecturer, ACP
  • 40. Disadvantages• We can simply examine whether respondents are more or less favorable to a topic• Interval is not equal• Total score has little clear meaning• What they think they should feel rather than how they do feel Dr.Asir John Samuel (PT), Lecturer, ACP
  • 41. Cumulative scales• Louis Guttman’s scalogram analysis• Statement in it form a cumulative series• Favorable item and unfavorable item• From total score one can estimate as to how a respondent has answered individual statement Dr.Asir John Samuel (PT), Lecturer, ACP
  • 42. Factor scales• Developed through factor analysis• Basis of intercorrelations of items Dr.Asir John Samuel (PT), Lecturer, ACP

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